Taken from https://github.com/bos/bloomfilter/pull/20

From fb79b39c44404fd791a3bed973e9d844fb084f1e Mon Sep 17 00:00:00 2001
From: Simon Jakobi <simon.jakobi@gmail.com>
Date: Fri, 12 Nov 2021 01:37:36 +0100
Subject: [PATCH] Fix build with GHC 9.2

The `FastShift.shift{L,R}` methods are replaced with `unsafeShift{L,R}`
introduced in base-4.5.

Fixes #19.
---
 Data/BloomFilter.hs         | 16 +++++------
 Data/BloomFilter/Hash.hs    | 15 +++++-----
 Data/BloomFilter/Mutable.hs | 20 +++++++-------
 Data/BloomFilter/Util.hs    | 55 ++++++-------------------------------
 bloomfilter.cabal           |  2 +-
 5 files changed, 34 insertions(+), 74 deletions(-)

diff --git a/Data/BloomFilter.hs b/Data/BloomFilter.hs
index 2210cef..6b47c21 100644
--- a/Data/BloomFilter.hs
+++ b/Data/BloomFilter.hs
@@ -78,8 +78,8 @@ import Control.DeepSeq (NFData(..))
 import Data.Array.Base (unsafeAt)
 import qualified Data.Array.Base as ST
 import Data.Array.Unboxed (UArray)
-import Data.Bits ((.&.))
-import Data.BloomFilter.Util (FastShift(..), (:*)(..))
+import Data.Bits ((.&.), unsafeShiftL, unsafeShiftR)
+import Data.BloomFilter.Util ((:*)(..))
 import qualified Data.BloomFilter.Mutable as MB
 import qualified Data.BloomFilter.Mutable.Internal as MB
 import Data.BloomFilter.Mutable.Internal (Hash, MBloom)
@@ -98,7 +98,7 @@ data Bloom a = B {
     }
 
 instance Show (Bloom a) where
-    show ub = "Bloom { " ++ show ((1::Int) `shiftL` shift ub) ++ " bits } "
+    show ub = "Bloom { " ++ show ((1::Int) `unsafeShiftL` shift ub) ++ " bits } "
 
 instance NFData (Bloom a) where
     rnf !_ = ()
@@ -172,7 +172,7 @@ singleton hash numBits elt = create hash numBits (\mb -> MB.insert mb elt)
 -- | Given a filter's mask and a hash value, compute an offset into
 -- a word array and a bit offset within that word.
 hashIdx :: Int -> Word32 -> (Int :* Int)
-hashIdx mask x = (y `shiftR` logBitsInHash) :* (y .&. hashMask)
+hashIdx mask x = (y `unsafeShiftR` logBitsInHash) :* (y .&. hashMask)
   where hashMask = 31 -- bitsInHash - 1
         y = fromIntegral x .&. mask
 
@@ -191,7 +191,7 @@ hashesU ub elt = hashIdx (mask ub) `map` hashes ub elt
 -- /still/ some possibility that @True@ will be returned.
 elem :: a -> Bloom a -> Bool
 elem elt ub = all test (hashesU ub elt)
-  where test (off :* bit) = (bitArray ub `unsafeAt` off) .&. (1 `shiftL` bit) /= 0
+  where test (off :* bit) = (bitArray ub `unsafeAt` off) .&. (1 `unsafeShiftL` bit) /= 0
           
 modify :: (forall s. (MBloom s a -> ST s z))  -- ^ mutation function (result is discarded)
         -> Bloom a
@@ -255,11 +255,11 @@ insertList elts = modify $ \mb -> mapM_ (MB.insert mb) elts
 -- is /still/ some possibility that @True@ will be returned.
 notElem :: a -> Bloom a -> Bool
 notElem elt ub = any test (hashesU ub elt)
-  where test (off :* bit) = (bitArray ub `unsafeAt` off) .&. (1 `shiftL` bit) == 0
+  where test (off :* bit) = (bitArray ub `unsafeAt` off) .&. (1 `unsafeShiftL` bit) == 0
 
 -- | Return the size of an immutable Bloom filter, in bits.
 length :: Bloom a -> Int
-length = shiftL 1 . shift
+length = unsafeShiftL 1 . shift
 
 -- | Build an immutable Bloom filter from a seed value.  The seeding
 -- function populates the filter as follows.
@@ -318,7 +318,7 @@ fromList hashes numBits = unfold hashes numBits convert
 logPower2 :: Int -> Int
 logPower2 k = go 0 k
     where go j 1 = j
-          go j n = go (j+1) (n `shiftR` 1)
+          go j n = go (j+1) (n `unsafeShiftR` 1)
 
 -- $overview
 --
diff --git a/Data/BloomFilter/Hash.hs b/Data/BloomFilter/Hash.hs
index 132a3a4..d071fd4 100644
--- a/Data/BloomFilter/Hash.hs
+++ b/Data/BloomFilter/Hash.hs
@@ -38,8 +38,7 @@ module Data.BloomFilter.Hash
     ) where
 
 import Control.Monad (foldM)
-import Data.Bits ((.&.), (.|.), xor)
-import Data.BloomFilter.Util (FastShift(..))
+import Data.Bits ((.&.), (.|.), unsafeShiftL, unsafeShiftR, xor)
 import Data.List (unfoldr)
 import Data.Int (Int8, Int16, Int32, Int64)
 import Data.Word (Word8, Word16, Word32, Word64)
@@ -91,11 +90,11 @@ class Hashable a where
              -> Word64           -- ^ salt
              -> IO Word64
     hashIO64 v salt = do
-                   let s1 = fromIntegral (salt `shiftR` 32) .&. maxBound
+                   let s1 = fromIntegral (salt `unsafeShiftR` 32) .&. maxBound
                        s2 = fromIntegral salt
                    h1 <- hashIO32 v s1
                    h2 <- hashIO32 v s2
-                   return $ (fromIntegral h1 `shiftL` 32) .|. fromIntegral h2
+                   return $ (fromIntegral h1 `unsafeShiftL` 32) .|. fromIntegral h2
 
 -- | Compute a 32-bit hash.
 hash32 :: Hashable a => a -> Word32
@@ -149,8 +148,8 @@ cheapHashes :: Hashable a => Int -- ^ number of hashes to compute
 cheapHashes k v = go 0
     where go i | i == j = []
                | otherwise = hash : go (i + 1)
-               where !hash = h1 + (h2 `shiftR` i)
-          h1 = fromIntegral (h `shiftR` 32)
+               where !hash = h1 + (h2 `unsafeShiftR` i)
+          h1 = fromIntegral (h `unsafeShiftR` 32)
           h2 = fromIntegral h
           h = hashSalt64 0x9150a946c4a8966e v
           j = fromIntegral k
@@ -163,7 +162,7 @@ instance Hashable Integer where
                                    (salt `xor` 0x3ece731e)
                   | otherwise = hashIO32 (unfoldr go k) salt
         where go 0 = Nothing
-              go i = Just (fromIntegral i :: Word32, i `shiftR` 32)
+              go i = Just (fromIntegral i :: Word32, i `unsafeShiftR` 32)
 
 instance Hashable Bool where
     hashIO32 = hashOne32
@@ -224,7 +223,7 @@ instance Hashable Word64 where
 -- | A fast unchecked shift.  Nasty, but otherwise GHC 6.8.2 does a
 -- test and branch on every shift.
 div4 :: CSize -> CSize
-div4 k = fromIntegral ((fromIntegral k :: HTYPE_SIZE_T) `shiftR` 2)
+div4 k = fromIntegral ((fromIntegral k :: HTYPE_SIZE_T) `unsafeShiftR` 2)
 
 alignedHash :: Ptr a -> CSize -> Word32 -> IO Word32
 alignedHash ptr bytes salt
diff --git a/Data/BloomFilter/Mutable.hs b/Data/BloomFilter/Mutable.hs
index edff1fc..0bb5cc9 100644
--- a/Data/BloomFilter/Mutable.hs
+++ b/Data/BloomFilter/Mutable.hs
@@ -65,9 +65,9 @@ module Data.BloomFilter.Mutable
 import Control.Monad (liftM, forM_)
 import Control.Monad.ST (ST)
 import Data.Array.Base (unsafeRead, unsafeWrite)
-import Data.Bits ((.&.), (.|.))
+import Data.Bits ((.&.), (.|.), unsafeShiftL, unsafeShiftR)
 import Data.BloomFilter.Array (newArray)
-import Data.BloomFilter.Util (FastShift(..), (:*)(..), nextPowerOfTwo)
+import Data.BloomFilter.Util ((:*)(..), nextPowerOfTwo)
 import Data.Word (Word32)
 import Data.BloomFilter.Mutable.Internal
 
@@ -86,9 +86,9 @@ new hash numBits = MB hash shft msk `liftM` newArray numElems numBytes
                 | numBits > maxHash = maxHash
                 | isPowerOfTwo numBits = numBits
                 | otherwise = nextPowerOfTwo numBits
-        numElems = max 2 (twoBits `shiftR` logBitsInHash)
-        numBytes = numElems `shiftL` logBytesInHash
-        trueBits = numElems `shiftL` logBitsInHash
+        numElems = max 2 (twoBits `unsafeShiftR` logBitsInHash)
+        numBytes = numElems `unsafeShiftL` logBytesInHash
+        trueBits = numElems `unsafeShiftL` logBitsInHash
         shft     = logPower2 trueBits
         msk      = trueBits - 1
         isPowerOfTwo n = n .&. (n - 1) == 0
@@ -109,7 +109,7 @@ logBytesInHash = 2 -- logPower2 (sizeOf (undefined :: Hash))
 -- | Given a filter's mask and a hash value, compute an offset into
 -- a word array and a bit offset within that word.
 hashIdx :: Int -> Word32 -> (Int :* Int)
-hashIdx msk x = (y `shiftR` logBitsInHash) :* (y .&. hashMask)
+hashIdx msk x = (y `unsafeShiftR` logBitsInHash) :* (y .&. hashMask)
   where hashMask = 31 -- bitsInHash - 1
         y = fromIntegral x .&. msk
 
@@ -125,7 +125,7 @@ insert mb elt = do
   let mu = bitArray mb
   forM_ (hashesM mb elt) $ \(word :* bit) -> do
       old <- unsafeRead mu word
-      unsafeWrite mu word (old .|. (1 `shiftL` bit))
+      unsafeWrite mu word (old .|. (1 `unsafeShiftL` bit))
 
 -- | Query a mutable Bloom filter for membership.  If the value is
 -- present, return @True@.  If the value is not present, there is
@@ -135,7 +135,7 @@ elem elt mb = loop (hashesM mb elt)
   where mu = bitArray mb
         loop ((word :* bit):wbs) = do
           i <- unsafeRead mu word
-          if i .&. (1 `shiftL` bit) == 0
+          if i .&. (1 `unsafeShiftL` bit) == 0
             then return False
             else loop wbs
         loop _ = return True
@@ -145,7 +145,7 @@ elem elt mb = loop (hashesM mb elt)
 
 -- | Return the size of a mutable Bloom filter, in bits.
 length :: MBloom s a -> Int
-length = shiftL 1 . shift
+length = unsafeShiftL 1 . shift
 
 
 -- | Slow, crummy way of computing the integer log of an integer known
@@ -153,7 +153,7 @@ length = shiftL 1 . shift
 logPower2 :: Int -> Int
 logPower2 k = go 0 k
     where go j 1 = j
-          go j n = go (j+1) (n `shiftR` 1)
+          go j n = go (j+1) (n `unsafeShiftR` 1)
 
 -- $overview
 --
diff --git a/Data/BloomFilter/Util.hs b/Data/BloomFilter/Util.hs
index 7f695dc..6ade6e5 100644
--- a/Data/BloomFilter/Util.hs
+++ b/Data/BloomFilter/Util.hs
@@ -2,15 +2,11 @@
 
 module Data.BloomFilter.Util
     (
-      FastShift(..)
-    , nextPowerOfTwo
+      nextPowerOfTwo
     , (:*)(..)
     ) where
 
-import Data.Bits ((.|.))
-import qualified Data.Bits as Bits
-import GHC.Base
-import GHC.Word
+import Data.Bits ((.|.), unsafeShiftR)
 
 -- | A strict pair type.
 data a :* b = !a :* !b
@@ -22,46 +18,11 @@ nextPowerOfTwo :: Int -> Int
 {-# INLINE nextPowerOfTwo #-}
 nextPowerOfTwo n =
     let a = n - 1
-        b = a .|. (a `shiftR` 1)
-        c = b .|. (b `shiftR` 2)
-        d = c .|. (c `shiftR` 4)
-        e = d .|. (d `shiftR` 8)
-        f = e .|. (e `shiftR` 16)
-        g = f .|. (f `shiftR` 32)  -- in case we're on a 64-bit host
+        b = a .|. (a `unsafeShiftR` 1)
+        c = b .|. (b `unsafeShiftR` 2)
+        d = c .|. (c `unsafeShiftR` 4)
+        e = d .|. (d `unsafeShiftR` 8)
+        f = e .|. (e `unsafeShiftR` 16)
+        g = f .|. (f `unsafeShiftR` 32)  -- in case we're on a 64-bit host
         !h = g + 1
     in h
-
--- | This is a workaround for poor optimisation in GHC 6.8.2.  It
--- fails to notice constant-width shifts, and adds a test and branch
--- to every shift.  This imposes about a 10% performance hit.
-class FastShift a where
-    shiftL :: a -> Int -> a
-    shiftR :: a -> Int -> a
-
-instance FastShift Word32 where
-    {-# INLINE shiftL #-}
-    shiftL (W32# x#) (I# i#) = W32# (x# `uncheckedShiftL#` i#)
-
-    {-# INLINE shiftR #-}
-    shiftR (W32# x#) (I# i#) = W32# (x# `uncheckedShiftRL#` i#)
-
-instance FastShift Word64 where
-    {-# INLINE shiftL #-}
-    shiftL (W64# x#) (I# i#) = W64# (x# `uncheckedShiftL64#` i#)
-
-    {-# INLINE shiftR #-}
-    shiftR (W64# x#) (I# i#) = W64# (x# `uncheckedShiftRL64#` i#)
-
-instance FastShift Int where
-    {-# INLINE shiftL #-}
-    shiftL (I# x#) (I# i#) = I# (x# `iShiftL#` i#)
-
-    {-# INLINE shiftR #-}
-    shiftR (I# x#) (I# i#) = I# (x# `iShiftRA#` i#)
-
-instance FastShift Integer where
-    {-# INLINE shiftL #-}
-    shiftL = Bits.shiftL
-
-    {-# INLINE shiftR #-}
-    shiftR = Bits.shiftR
diff --git a/bloomfilter.cabal b/bloomfilter.cabal
index 821a5d7..c621f7f 100644
--- a/bloomfilter.cabal
+++ b/bloomfilter.cabal
@@ -18,7 +18,7 @@ extra-source-files: README.markdown cbits/lookup3.c cbits/lookup3.h
 library
   build-depends:
     array,
-    base       >= 4.4 && < 5,
+    base       >= 4.5 && < 5,
     bytestring >= 0.9,
     deepseq
   exposed-modules:  Data.BloomFilter
